The Riley County Planning & Development Department has maps produced by the Federal Emergency Management Agency that indicate where the floodplains are for all of the unincorporated area of the County. For assistance in determining flood risk on a particular property, please contact Steve Higgins at (785) 537-6332 or email Steve...

The 500-year floodplain is the area that could experience a flood having a .2% probability of occurring in any given year. It is an area that is not regulated by floodplain regulations and therefore building is permitted provided all other requirements of the County Zoning & Subdivision Regulations are met. One should always keep in mind that any area, even those outside of designated floodplains, can still flood. Even though the probability of such occurrences in these areas is generally lower, there can always be micro events and unusual circumstances that may occur to cause localized flooding of any property. For more information about the floodplain, please contact Steve Higgins at (785) 537-6332 or email Steve...

The 100-year floodplain represents a potential flood area that has a 1% probability of being equaled or exceeded in any given year. It is the area that is regulated by floodplain regulations as required by the Federal Emergency Management Agency. Generally, you can build in the 100-year floodplain if the floor of the structure is elevated one foot above the Base Flood Elevation (BFE). Commercial & industrial structures have the option of being flood-proofed. All construction within the 100-year floodplain requires a Floodplain Development Permit before construction begins. All construction within the 100-year floodplain requires a Floodplain Development Permit before construction begins. For more information about the floodplain, please contact Steve Higgins at (785) 537-6332 or

The floodway is the area within the 100-year floodplain that must remain unobstructed to carry the 100-year flood discharge (i.e. Base Flood). Generally, it is very difficult to construct any structure within the floodway because the structure must be determined, not by an engineer not to obstruct flood flows in any way or create a substantial rise in the base flood elevation. These are very difficult standards to meet except in cases of very limited obstructions such as poles, fence posts, etc. For more information on the methodology that must be used to determine this no-rise in flood heights, please contact Steve Higgins at (785) 537-6332 or email Steve...